The present invention relates to an arrangement for controlling the temperature of air being fed to a vehicle engine, the arrangement comprising an engine compartment in which said engine is arranged, said engine compartment being provided with an ambient air intake allowing an airflow into said engine compartment, said engine being provided with an engine air intake arranged inside the engine compartment, and an air fan for forcing the airflow via the ambient air intake into the inside of the engine compartment.
The invention also relates to a method for controlling the temperature of air being fed to a vehicle engine arranged in an engine compartment, said engine being provided with an engine air intake arranged inside the engine compartment, said method composing controlling an air fan for forcing an airflow of ambient air into the engine compartment.
The invention is applicable on working machines within the field of industrial construction machines, in particular load receivers such as articulated haulers or dumpers. Although the invention will be described hereinafter with respect to an articulated hauler, the invention is not restricted to this particular machine, but may also be used in other heavy working machines or construction equipment. Generally, the invention could be used in virtually any type of vehicle with a combustion engine.
In connection with transportation of heavy loads, a working machine in the form of an articulated hauler is frequently used. Such a working machine may be operated with large and heavy loads in areas where there are no roads, for example for transports in connection with road or tunnel building, sand pits, mines, forestry and similar environments. Thus, an articulated hauler is frequently used in rough terrain and on a slippery ground where no regular roads are present.
An articulated hauler is a frame-steered working machine having a container for receiving and transporting a load. Such a working machine comprises a front section with a front frame and a first set of wheels, and a rear section with a rear frame and a second set of wheels. A pivot joint is arranged between the front section and the rear section allowing the front section and the rear section to pivot relative to each other about an axis extending in the vertical direction. Furthermore, the working machine comprises means for steering the working machine by pivoting the front section and the rear section relative to each other about the vertical pivot axis. The steering means normally includes a pair of hydraulic cylinders.
The front section is a tractor for driving the working machine and the rear section is provided with the container for receiving the load. In order to optimize the load capacity, the front section is normally shorter than the rear section. Usually the front section has one wheel axle, whereas the rear section has two wheel axles mounted as bogie axles.
The above-mentioned types of working machines are normally operated by means of combustion engines. For this reason, there is a demand for arrangements which provide an inflow of air to the engine in order for the combustion process in the engine to take place in a correct manner.
It is also known that a combustion engine can be equipped with a turbocharger device which, according to known technology, comprises a turbine which is driven by the exhaust gases produced by the engine. The turbine is connected to a compressor, by means of which a flow of air to the engine is compressed before being fed to the engine. In this manner, an increased amount of input air can be compressed and fed to the engine, thereby increasing the power of the engine.
When operating a combustion engine with a turbocharger device, for example in a working machine as described above, it is consequently important to feed an inflow of air from the surrounding atmosphere to the engine. Obviously, combustion engines which are not equipped with a turbocharger device also need a sufficient inflow of air.
Furthermore, there is a need to control the temperature of the airflow being fed to the engine. More precisely, the temperature of the air to the engine should be adapted to the operating conditions of the combustion engine and the vehicle in question. For example, in order to fulfil requirements regarding low emissions of harmful exhaust gases, there is a requirement for a relatively high temperature of the exhaust gases. This corresponds to a need for a relatively high temperature of the inflow of air to the engine in certain operating modes of the engine. This corresponds for example to a situation in which the engine has just been started and is idling.
On the other hand, when the engine is operated so as to provide a relatively high output torque, for example when using a turbocharger device, there is a need to decrease the temperature of the input air the engine. For this reason, a turbocharger device is often provided with a charge air cooler which is arranged to decrease the temperature of the input air guided through it.
According to known technology, an increased temperature of the air to the engine can obtained through operating the engine in certain heating modes in which fuel is added in order to raise the exhaust gas temperature. Even though the aim of raising the exhaust gas temperature is obtained in is manner, the method leads to a disadvantage since it increases the fuel consumption of the engine.
The patent document US 2007/0197157 teaches a system for managing engine intake air temperature, especially under colder ambient conditions and for systems comprising exhaust gas after treatment devices. The system uses two conduits, one that receives intake air from outside the vehicle, and one that receives intake air from the engine compartment. A flow control device is used to control from which source the intake air is taken and the flow control device is controlled based on the engine operating temperature.
Although the system according to US 2007/0197157 is directed to the purpose of controlling the temperature of the intake air temperature, there is still a demand for more improved arrangements and methods, in particular for adapting the temperature control of the inflow of air to specific operational conditions of an engine so that for example demands for low emissions of harmful exhaust gases can be reached.
It is desirable to solve the above-mentioned problem and to provide an improved arrangement and method for controlling the temperature of the input air being fed to an engine, in particular so that the air temperature is adapted in a correct manner to the operating conditions of the engine and the vehicle in a manner which is efficient as regards cost, fuel consumption and reduction of exhaust emissions.
It is also desirable to provide a simple and cost-effective solution for controlling the temperature of the input air.
According to an aspect of the present invention, an arrangement of the kind as mentioned initially which is characterized in that the engine air intake is arranged in a position allowing at least a substantial part of said airflow to enter the engine air intake.
In this context, the term “substantial part” refers to the fact that, according to the invention, a relatively high amount of the airflow which enters the ambient air intake can also be guided further so as to reach the engine air intake. This is particularly useful during operational conditions in which the engine needs an inflow of relatively cold air.
An advantage with the invention is that it reduces fuel consumption of the engine since the engine does not need to be operated in any particular heating mode (in which fuel is added) in order to raise the exhaust temperature.
A further advantage of the invention is that it constitutes an energy-efficient solution for controlling air temperature due since it uses waste heat from the engine to increase the temperature of air which is fed into the engine.
According to an embodiment, the invention constitutes a “self-regulating” solution which provides a boost effect in the sense that when the engine needs colder air, the speed of the air fan is increased (which leads to a higher degree of cooling in the charge air cooler), which at the same increases the inflow into the engine compartment and a larger part of the input air to the engine will be constituted by colder air.
A further advantage of the invention is that the service interval of the engine's air filter can be extended since the engine air intake can be located inside the engine compartment, which is a relatively clean place on a working machine such as an articulated hauler.
According to an embodiment of the invention a control unit is arranged to control the air fan for providing said airflow to the engine air intake. Suitably, the air fan is arranged for selectively being operated in a first mode of operation with a relatively high speed for providing an airflow from said ambient air intake to said engine air intake, thereby decreasing the temperature of the air flowing into said engine air intake; or a second mode of operation with a relatively low speed for providing an airflow from within the engine compartment to said engine air intake, thereby increasing the temperature of the air flowing into said engine air intake. In this manner, an efficient control of the air temperature can be obtained which is adapted to various operational conditions of the engine.
According to an embodiment, the speed of the air fan is controlled depending on the operational condition of said engine. This means that the speed of the air fan can be chosen in order to provide a suitable amount of intake air for each given type of operation of the engine.
Furthermore, when the engine needs warmer air, the speed of the charge air cooler's fan can be decreased, which at the same time reduces the inflow of air into the engine compartment, and a higher proportion of the intake air to the engine will be constituted by air which has been heated by the engine.
The method according to the invention can be performed through execution of a computer program, which comprises program code means for performing all the steps according to the method according to the invention when the program is run on a computer. In particular, an aspect of the invention comprises a computer system for implementing a method for controlling the temperature of air being fed to a vehicle engine arranged in an engine compartment, said engine being provided with in engine air intake arranged inside the engine compartment, said method comprising controlling an air fan for forcing an airflow of ambient air into the engine compartment, the computer system comprising a processor operable to providing said airflow in a way enabling at least a substantial part of the airflow to enter the engine air intake.